The present invention relates to a technique for manufacturing a semiconductor device, and more particularly to a technique that encapsulates an electronic component such as a semiconductor chip mounted on a wiring board with a resin.
For semiconductor packages, there is a single side encapsulation type package including a wiring board, a semiconductor chip mounted on the wiring board, and an encapsulation resin provided on the wiring board so as to cover the semiconductor chip.
In forming the encapsulation resin of this semiconductor package, a mold including a lower mold supporting the back surface side of a wiring board and an upper mold facing the lower mold is used. The upper mold includes a recessed portion forming a cavity surrounding a semiconductor chip and a flat portion contacting the surface of a wiring board around the cavity (see Japanese Unexamined Patent Publication No. 2000-058571 and Japanese Unexamined Patent Publication No. 2006-313801, for example).
The wiring board includes an insulating film, a wiring pattern formed on this insulating film, and a solder resist covering this wiring pattern. The solder resist is formed on projecting portions relatively protruding on the wiring pattern, and formed on recessed portions other than the projecting portions because of the thickness of the wiring pattern. Therefore, a gap is generated between the solder resist and the upper mold on the recessed portion, and a resin sometimes leaks through this gap. On the other hand, in order to suppress the resin leakage, when the upper mold and the lower mold are pressed against each other strongly, the wiring board on the projecting portions is likely to be damaged (for example, Japanese Unexamined Patent Publication No. 2000-058571 and Japanese Unexamined Patent Publication No. 2006-313801).
In view of these problems, Japanese Unexamined Patent Publication No. 2000-058571 describes that a wall-shaped clamp block surrounding the cavity is provided relatively vertically movably to the upper mold, the clamp block is pressed downward using a pressuring mechanism, and the lower end surface of the clamp block is pressed against portions adjacent to the cavity on the top surface of the wiring board for stopping the leakage of a resin. The clamp block described in Japanese Unexamined Patent Publication No. 2000-058571 is disposed at a location adjacent to the cavity, or in the cavity.
It is noted that Japanese Unexamined Patent Publication No. 2005-101407 describes a technique in which a block pin is provided on an upper mold. This block pin contacts the top surface of a lower mold on the outer side of a wiring board, and the lower mold is pressed down in clamping for suppressing the deformation or cracking or the like of the wiring board.